Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 271902 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 302 PM EDT Tue Jun 27 2017 .SYNOPSIS... A moisture-starved cold front will cross central NC this afternoon. Canadian high pressure will follow and crest over the southern middle Atlantic states Wed and Wed night. && .NEAR TERM /TODAY/... As of 1020 AM EDT Tuesday... Just minor adjustments required to the near term forecast, primarily to decrease PoPs in the west and tweak temp/dewpoints as temperatures are averaging 2-3 degrees warmer than expected. 12Z upper air analysis depicts a modest mid-level trough exiting the TN Valley this morning. This feature accompanied by 30-40m height falls. While synoptic lift present, atmosphere over central NC not all that moist, and minimal moisture advection noted in the analysis. Still expect the highest coverage of a few showers and possibly an isolated t-storm to occur this afternoon-early evening across the eastern and southern sections of our forecast area. The threat for showers does not look all that impressive across the western Piedmont so have lowered PoP a bit in this region. Early morning dewpoints were in the upper 50s to lower 60s. As mixing ensues late morning-early afternoon, expect dewpoints to drop into the low-mid 50s most places. Mid-morning temperatures have warmed into the low-mid 70s. Temperatures should slow their rise as mid/upper level clouds thicken this afternoon. Still expect enough heating to warm into the low-mid 80s. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... As of 400 AM EDT Tuesday... The system will be east of the area by early tonight with decreasing cloudiness leading to mostly clear skies after midnight as high pressure builds in from the northwest. Mins will tumble in the drying airmass with the clearing above, and most areas should be in the upper 50s by sunrise Wednesday. Skies will remain clear through Wednesday night as the high moves across the area, with highs Wednesday edging up a bit under strong sun to reach the low and mid 80s, with mins Wednesday night in the lower 60s. && .LONG TERM /Thursday through Tuesday/...
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As of 300 PM EDT Tuesday... A subtle upper level low in vicinity of the TX gulf coast this afternoon is progged to meander slowly NE into the Deep South on Thu before deamplifying/lifting NE across portions of the Carolinas on Fri. Expect dry conditions to persist on Thu, followed by an increasing potential for convection Fri afternoon/evening as the deamplifying upper wave lifts NE across the Carolinas and southerly return flow strengthens (temps/moisture rebound toward climatology). Cyclonic flow aloft will strengthen over the eastern US this weekend as a potent upper level low (currently in Alberta) digs SE into the Great Lakes (Sat) and lifts NE across New England (Sun). Broad troughing aloft will suppress/confine the sub-tropical ridge to the FL peninsula and aid in the development/maintenance of a pronounced surface trough east of the Appalachians over the weekend. With the above in mind, expect above normal chances for convection and near normal temperatures Sat/Sun. Forecast confidence decreases early next week. Several MCS`s are expected to develop upstream of the region Mon/Tue as shortwave energy in NW flow aloft progresses from the Rockies into the Central Plains/Central MS River Valley. In general, temperatures are expected to increase as flow aloft over the Mid-Atlantic weakens/flattens and the previously suppressed sub- tropical ridge expands northward from FL into the Deep South/ Southeast, and the relative best potential for convection should shift along/east of the Hwy 1 corridor, though coverage/timing may ultimately depend on the evolution of upstream MCS`s. -Vincent
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&& .AVIATION /18Z Tuesday through Sunday/...
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As of 110 PM EDT Tuesday... VFR parameters expected across central NC through Thursday. An upper level disturbance and attendant sfc front will cross central NC this afternoon, and exit our region early this evening. This weather feature will cause an increase in mid/upper level cloudiness, along with a threat for isolated showers and possibly a thunderstorm. The convective threat appears highest along and east of highway 1. Even so, with coverage expected to be no worse than isolated, threat appears too minimal to include in the aerodrome forecast for KFAY and KRWI. Clouds will decrease this evening with mostly clear skies anticipated overnight, persisting Wednesday through early Thursday. An increasing sly low level flow late Thursday into Thursday night will usher moisture into our region, leading to the probability of low cloud cover by early Friday morning. These low clouds, if they occur, should burn off by mid morning. A persistent low level sly flow is expected Friday through Sunday, leading to an increasingly wet atmosphere and increased chances for sub-VFR parameters. This will lead to periods of low clouds and patchy fog each morning and a chance for scattered afternoon-evening convection each day.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...WSS SHORT TERM...mlm LONG TERM...Vincent AVIATION...WSS

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